Systems and Methods for the Continuous On-Site Production of Peroxycarboxcylic Acid Solutions

Abstract

Methods and systems for on-site production of peroxycarboxcylic acid compositions, and in particular, nonequilibrium compositions of peracetic acid (PAA) enable the economical and safe production of PAA on-demand at the point of use. The methods and systems control flow rates and proportions of feedstocks/reactants, perform the required sequence of reaction steps to produce high yield peroxycarboxcylic acid solutions in a continuous manner, and provide optimal reaction time and reactant mixing for continuous and safe on-site production.

What is claimed is: 
     
         1 . A method for the continuous production of non-equilibrium peracetic acid solutions containing biocidal concentrations of peroxycarboxylic acids, the method comprising:
 providing a source of hydrogen peroxide having an initial pH of less than 7.0;   diluting the hydrogen peroxide with water to create a diluted solution having a concentration which is less than 10% weight/volume;   adding an alkali metal hydroxide to the diluted solution to adjust the pH to a pH in a range of approximately 10.0 to approximately 13.5;   reacting the diluted solution with an O-acetyl or N-acetyl donor;   vigorously mixing the solution.   
     
     
         2 . The method of  claim 1  further including the step of controlling the stoichiometry of the peroxide component with respect to the acetyl donor to bias the reaction in favor of either producing peracetic acid or producing a solution having a specified remaining concentration of peroxide. 
     
     
         3 . The method of  claim 1  wherein the alkali metal hydroxide is sodium hydroxide. 
     
     
         4 . The method of  claim 1  wherein the alkali metal hydroxide is potassium hydroxide. 
     
     
         5 . The method of  claim 1  wherein the O-acetyl donor is triacetin. 
     
     
         6 . The method of  claim 1  wherein the step of mixing the solution includes producing a turbulent flow having high shear within the solution and having a Reynolds number of 500 or greater. 
     
     
         7 . The method of  claim 1  including the step of vigorously mixing the solution following the diluting step. 
     
     
         8 . The method of  claim 7  further including the step of vigorously mixing the solution following the step of adjusting the pH to a range of approximately 10.0 to approximately 13.5. 
     
     
         9 . The method of  claim 1  including the step of injecting an acid into the solution at a preselected reaction time. 
     
     
         10 . The method of  claim 9  further including the step of mixing the solution and creating a turbulent flow therein having a Reynolds number of 500 or greater. 
     
     
         11 . The method of  claim 1  further including the step of adjusting the ratio of peracetic acid to hydrogen peroxide in non-equilibrium solution to provide an excess of hydrogen peroxide therein. 
     
     
         12 . the method of  claim 11  wherein the excess of hydrogen peroxide is in a range approximately 0.40 lb to approximately 5.0 lb per pound of peracetic acid produced. 
     
     
         13 . A system for the continuous production of non-equilibrium peracetic acid solutions containing biocidal concentrations of peroxycarboxylic acids, the system comprising:
 a source of a continuous supply of water;   a source of a continuous supply of reactants;   a control system including a flow sensor structured and arranged to control the continuous supply of water and reactants to the system;   a high shear mixing device adapted to controllably mix the water and the reactants in a flow environment having a Reynolds number of 500 or greater;   a continuous tube reactor adapted to receive the water and the reactants from the mixer and to contain the reactants for a residence time within the reactor of sufficient duration to form a single phase solution; and   a discharge system for removing the non-equilibrium peracetic acid solution from the system.   
     
     
         14 . The system of  claim 13  wherein the continuous tube reactor comprises at least one mixing coil. 
     
     
         15 . The system of  claim 13  wherein the static mixer is structured and arranged to create a flow of the eater and the reactant mixture having a Reynolds number of 500 or greater. 
     
     
         16 . The system of  claim 13  wherein the continuous tube reactor includes a first segment and a second segment, each segment having a length and a diameter extending along its length, the diameter of the first segment being larger than the diameter of the second segment. 
     
     
         17 . The system of  claim 13  wherein the source of continuous water supply and the source of a continuous supply of reactants comprises a plurality of water-powered proportional pumps connected in series. 
     
     
         18 . The system of  claim 13  further including at least one parallel continuous production system, each of the at least one parallel systems comprising:
 a source of a continuous supply of water; 
 a source of a continuous supply of reactants; 
 a control system including a flow sensor structured and arranged to control the continuous supply of water and reactants to the system; 
 a static mixer adapted to controllably mix the water and the reactants; 
 a continuous tube reactor adapted to receive the water and the reactants from the mixer and to contain the reactants for a residence time within the reactor of sufficient duration to form a single phase solution; and 
 a discharge system for removing the non-equilibrium peracetic acid solution from the system. 
 
     
     
         19 . The system of  claim 13  wherein the source of a continuous supply of reactants comprises a plurality of bladders, each containing a respective one of the reactants. 
     
     
         20 . The system of  claim 13  further including at least one pH probe adapted to monitor and to create a measurement of the pH of the non-equilibrium peracetic acid solution in the discharge system; 
     
     
         21 . The system of  claim 20  including a system for adjusting the addition of a quantity of acid into the product.